1. Field of the Invention
This invention relates to the manufacture of containers and more particularly to a novel and highly effective method and apparatus enabling the manufacture of inexpensive containers for liquids and to containers produced by the method and apparatus. The containers are especially adapted for use in the laboratory.
2. Description of the Prior Art
The manufacture of containers including containers for liquids has of course been known for thousands of years. However, the manufacture of containers continues to evolve because of an unmet need for containers that are inexpensive enough to be disposable yet conform to a number of stringent standards. Among the standards are precise control of container volume; the ability to accept writing, calibration marks, etc.; the ability to stand upright; the ability to pour liquids without dribbling down the outside of the container; color; transparency, translucence or opacity; resistance to attack by various solvents, acids and bases; resistance to oxidation in the atmosphere; resistance to breakage; the ability to withstand extremes of temperature; and, of course, a watertight construction to prevent undesirable leakage.
To meet these needs, increasing use has been made of plastics in recent decades. Plastics are generally inexpensive and possess many properties that render them suitable for use in the manufacture of containers, including containers for use in the laboratory. Moreover, efficient techniques for making containers from a plastic are known. In particular, the use of ultrasonic welding to seal plastics is known. For example, a Sager U.S. Pat. No. 4,411,720 discloses an ultrasonic welding method for sealing a thermoplastic cap to the neck of a thermoplastic container. However, the prior art does not provide a container that is made of inexpensive plastic by a process employing ultrasonic welding and that meets all of the needs of modern laboratories.